TWI780964B - Recovery method of platinum - Google Patents

Abstract

The present invention discloses a recovery method of platinum. According to the recovery method, a leaching liquor is firstly added into a Pt-containing waste liquid, and then a first solvent is added into a first liquid mixture consisting of the leaching liquor and the Pt-containing waste liquid for conducting a first solvent extraction. Subsequently, a second solvent is used to apply a second solvent extraction process to a second liquid mixture consisting of the first solvent and the first liquid mixture, and then an alkaline reducing agent is added into a third liquid mixture consisting of the second solvent and the second liquid mixture for activating the reduction of platinum ions in the third liquid mixture. After that, adding a first refining agent in to a fourth liquid mixture consisting of the alkaline reducing agent and the third liquid mixture, and subsequently adding a second refining agent in to a fifth liquid mixture consisting of the first refining agent and the fourth liquid mixture. In a last step of the recovery method, it is utilized suction filtration apparatus to filter a Pt powder out of a sixth liquid mixture consisting of the second refining agent and the fifth liquid mixture, and then rinsing and drying the Pt powder, thereby obtaining a plurality of Pt granules with purity of 99%.

Description

Methods of recovering platinum

The invention relates to the technical field of precious metal recovery, in particular to a method for recovering platinum.

Indium (In), rhodium (Rh), gold (Au), silver (Ag), platinum (Pt), palladium (Pd) and other elements belong to platinum group metals (Platinum Group Metals, PGM), with high melting point and acid corrosion resistance It is a metal with high industrial value because of its excellent properties. In particular, the average content of platinum in the earth's crust is only 2.0 g/t, while the average content of more common gold in the earth's crust is 4.0 g/t, and the average content of silver in the earth's crust is also 70 g/t . It can be seen that the platinum series is rarer than gold and silver.

At present, platinum has been widely used in the industrial manufacturing of various household products, including: electronic chips, electroless plating of glass, electroless plating of plastics, petrochemical industry, jewelry, currency, automotive catalytic converters, etc. It is conceivable that the annual demand for platinum metal in the world has substantially exceeded the available supply, thus causing the price of platinum metal to be very expensive. Based on the aforementioned reasons, platinum-containing waste is very valuable for resource recovery and regeneration.

Document 1 discloses a method for recovering platinum from catalyst waste. Here, the first document is: Barakat et. al, "Recovery of Platinum from Spent Catalyst", Hydrometallurgy, Vol 72, Issues 3–4, March 2004, Pages 179-184. According to the disclosure of Document 1, the catalyst waste was refluxed with aqua regia (ie, leaching solution) for 1.5 hours to dissolve platinum in the aqua regia, wherein the liquid-solid ratio of aqua regia to catalyst waste was 7.5. Next, platinum was separated from the leaching solution with a trioctylamine solvent, and then ammonium chloride was added to precipitate platinum in the form of diammonium hexachloroplatinate. Finally, the precipitate of diammonium hexachloroplatinate was decomposed by ignition to obtain platinum powder with a purity of 95%-97.9%.

It can be seen from the above description that the method taught by the prior art can only recover platinum powder with a purity of 95%-97.9% from the catalyst waste. In other words, the conventional methods for recovering platinum from catalyst waste still have room for improvement. In view of this, the inventor of the present invention has tried his best to research and create, and has finally developed a method for reclaiming platinum of the present invention.

The main purpose of the present invention is to provide a method for recovering platinum, which is achieved through the use of a leaching solution, a first solvent, a second solvent, an alkaline reducing agent, a first refining agent, and a second refining agent. A platinum metal powder with a purity of at least 99% can be successfully recovered from a platinum-containing waste liquid.

In order to achieve the above object, the present invention proposes an embodiment of the method for recovering platinum, comprising the following steps: (1) adding a leaching liquor (leaching liquor) into a container filled with a platinum-containing waste liquor to form a first mixed liquor; (2) adding a first solvent into the container to obtain a second mixed solution, and then uniformly stirring the second mixed solution at room temperature; (3) adding a second solvent into the container to obtain a third mixed solution, and then uniformly stirring the third mixed solution at room temperature; (4) adding an alkaline reducing agent into the container to obtain a fourth mixed solution, and then uniformly stirring the fourth mixed solution at a first treatment temperature; (5) adding a first refining agent into the container to obtain a fifth mixed liquor, and then uniformly stirring the fifth mixed liquor at the first treatment temperature; (6) adding a second refining agent into the container to obtain a sixth mixed solution, and then uniformly stirring the sixth mixed solution at a second processing temperature; (7) A platinum metal powder comprising a plurality of platinum particles is filtered out from the sixth mixed solution by air suction filtration; and (8) washing and drying the platinum metal powder; Wherein, the first solvent is any one selected from the group consisting of ethanol: ethylene glycol, ethanol: isopropanol, ethanol: n-butanol, ethanol: amyl alcohol, and ethanol: tetrahydrofuran; Wherein, the second solvent is selected from the group consisting of formic acid: methyl formate, formic acid: propyl formate, acetic acid: ethyl acetate, acetic acid: butyl acetate, and propionic acid: methyl propionate either; Wherein, the basic reducing agent is selected from sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium citrate, potassium citrate, sodium formate, potassium formate, sodium acetate, potassium acetate, sodium propionate, and Any one of the group consisting of potassium propionate; Wherein, the first refining agent is selected from 3-(bromomethyl)thiophene, 3-(bromoacetyl)thiophene, 2-(2-bromoacetyl)thiophene, 2-bromo-3-( Any one of the group consisting of bromomethyl)thiophene, 2,3-dibromophenyl[b]thiophene, and 2,5-dibromodithiophene[3,2-b]thiophene; Wherein, the second refining agent is selected from pyrrole, 1-(2-bromoethyl)-1H-pyrrole, 2-(trichloroacetyl)pyrrole, pyrrole-3-hydroxy acid, 2-bromothiophene , 3-bromothiophene, 3-bromothiophene-2-hydroxy acid, 2,3-dibromothiophene, 3,4-dibromothiophene, 2,5-dibromothiophene, and 2,4-dibromothiophene any of the groups.

In order to more clearly describe a method for recovering platinum proposed by the present invention, preferred embodiments of the present invention will be described in detail below with reference to the drawings.

Please refer to Fig. 1, which shows a flow chart of a method for recovering platinum of the present invention. The invention proposes a method for recovering platinum, which is used for recovering platinum metal with high purity from a platinum-containing waste liquid. In a feasible embodiment, the platinum-containing waste liquid has a platinum weight percentage, and the platinum weight percentage is between 0.1 wt% and 20 wt%. Moreover, the platinum-containing waste liquid is an acidic liquid and cannot contain gold and/or silver. In more detail, according to different sources, the platinum-containing waste liquid contains platinum (Pt) and/or at least one platinum derivative, and the platinum derivative is platinum monoxide (PtO), platinum dioxide ( PtO ₂ ), platinum oxide (Pt ₃ O ₄ ), platinum dichloride (PtCl ₂ ), platinum tetrachloride (PtCl ₄ ), platinum hexachloride (PtCl ₆ ), chloroplatinic acid (H ₂ PtCl ₆ ), Platinum acetate (Pt(CH ₃ COO) ₂ ), platinum sulfide (PtS).

In particular, if the platinum-containing waste liquid contains bromoplatinic acid (H ₂ PtBr ₆ ), platinum dibromide (PtBr ₂ ), platinum tetrabromide (PtBr ₄ ), or organic platinum compounds (Organic Platinum Complex), then it is not suitable to use the method of the present invention to reclaim platinum from such platinum-containing waste liquid.

It is worth noting that the platinum weight percentage of the platinum-containing waste liquid cannot be lower than 0.1 wt% or higher than 20 wt%. When the weight percentage of platinum is less than 0.1 wt%, the method of the present invention cannot successfully recover platinum metal powder (ie, a plurality of platinum particles) from the platinum-containing waste liquid. On the other hand, when the platinum weight percentage is higher than 20 wt%, it is easy to generate specific platinum derivatives that will affect refining in the platinum-containing waste liquid, such as: platinum dioxide (PtO ₂ ), platinum oxide (Pt ₃ O ₄ ) and so on. Furthermore, if the platinum-containing waste liquid contains other metal components (such as: palladium), the concentration of other metal components cannot exceed 12wt%. It is further supplemented that the main reason why the present invention restricts the platinum-containing waste liquid to be an acidic solution is that the acidic solution can dissolve platinum derivatives therein.

As shown in FIG. 1 , the method flow is to first execute step S1: adding a leaching liquor into a container containing a platinum-containing waste liquor to form a first mixed liquor. In a feasible embodiment, the leaching solution is aqua regia or aqua regia Lefort. Continuing, the method flow proceeds to step S2: adding a first solvent into the container to obtain a second mixed solution, and then uniformly stirring the second mixed solution at room temperature (20-25° C.). It should be understood that, in the steps S1-S2, the platinum-containing waste liquid, the leaching liquid and the first solvent are sequentially added into a container of a homogeneous mixer. In a feasible embodiment, the container is made of a material, and the material can be Pyrex glass (Pyrex glass), Duran glass (Duran glass), polystyrene (PP), or polyethylene terephthalate Ethylene formate (PET).

According to the design of the present invention, the single batch consumption of the platinum-containing waste liquid is between 1.5 liters and 3.5 liters, and the single batch consumption of the first solvent is between 0.5 liters and 1 liter. For example, the single batch consumption of the platinum-containing waste liquid can be 1.5 liters, 2 liters, 2.5 liters, 3 liters, or 3.5 liters, and the single batch consumption of the first solvent can be 0.5 liters, 0.75 liters, or 1 liter. And, in a feasible embodiment, the first solvent can be ethanol:ethylene glycol, ethanol:isopropanol, ethanol:n-butanol, ethanol:pentanol, or ethanol:tetrahydrofuran, and has a ratio of, for example, 1:1 , 2:1, 4:1, or 5:1 volume mixing ratio (v/v).

After step S2 is completed, the method flow is to execute step S3: adding a second solvent into the container to obtain a third mixed solution, and then uniformly stirring the third mixed solution at room temperature (20-25° C.). In the step S3, the single batch amount of the second solvent is between 0.1 liter and 0.25 liter. For example, the single batch amount of the second solvent can be 0.1 liter, 0.15 liter, 0.2 liter, or 0.25 liter. And, in a feasible embodiment, the second solvent can be formic acid: methyl formate, formic acid: propyl formate, acetic acid: ethyl acetate, acetic acid: butyl acetate, or propionic acid: methyl propionate, and has For example, a volume mixing ratio (v/v) of 1:1, 1:2, 1:4, or 1:5.

After step S3 is completed, the method flow is to execute step S4: adding an alkaline reducing agent into the container to obtain a fourth mixed solution, and then uniformly stirring the fourth mixed solution at a first processing temperature. In the step S4, the basic reducing agent is used in a single batch between 50 grams and 200 grams, so that the basic reducing agent has an overnormal concentration in the second mixed solution. For example, the single batch dosage of the basic reducing agent can be 50 grams, 100 grams, 125 grams, 150 grams, or 200 grams. And, in a feasible embodiment, the alkaline reducing agent can be sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium citrate, potassium citrate, sodium formate, potassium formate, sodium acetate, potassium acetate, propane sodium propionate, or potassium propionate, and the first treatment temperature is between 40°C and 45°C.

It is worth noting that, in the step S2, the first solvent extraction process is performed on the second mixed liquid with the first solvent. Next, in the step S3, a second solvent extraction process is performed on the third mixed liquid by using the second solvent. Continuing, in the step S4, the alkaline reducing agent is used to perform a platinum reduction treatment on the fourth mixed solution. Therefore, after the step S4 is completed, samples can be taken from the fourth mixed solution to obtain a plurality of reduced platinum particles. At this time, the platinum weight percentage of the fourth mixed solution will increase to 60 wt%, but will not exceed. The main reasons include: (a) part of the platinum is adsorbed by the carbon element of the alkaline reducing agent; (b) part of the platinum is adsorbed by other metal atoms (such as Ni, Cu); and (c) part of the platinum turns into other platinum derivatives.

After step S4 is completed, the method flow is followed by step S5: adding a first refining agent into the container to obtain a fifth mixed liquor, and then uniformly stirring the fifth mixed liquor at the first treatment temperature (40-45° C.). Mixture. In the step S5, the single batch dosage of the first refining agent is between 25 mg and 100 mg, and its purity is between 95% and 99%. For example, the single batch dosage of the first refining agent can be 25 mg, 50 mg, 75 mg, or 100 mg. And, in a feasible embodiment, the first refining agent can be, for example, 3-(bromomethyl)thiophene, 3-(bromoacetyl)thiophene, 2-(2-bromoacetyl)thiophene, 2 Derivatives of thiol series such as -bromo-3-(bromomethyl)thiophene, 2,3-dibromophenyl[b]thiophene, or 2,5-dibromodithiophene[3,2-b]thiophene things.

Therefore, after the step S5 is completed, samples can be taken from the fifth mixed solution to obtain a plurality of reduced platinum particles. At this time, the platinum weight percentage of the fifth mixed solution will increase to 60-70 wt%, but will not exceed. The main reasons include: (a) part of the platinum is still adsorbed by the carbon element of the alkaline reducing agent; and (b) there are still platinum derivatives that have not been decomposed into platinum.

After step S5 is completed, the method flow is then executed in step S6: adding a second refining agent into the container to obtain a sixth mixed liquor, and then uniformly stirring the sixth mixed liquor at a second processing temperature (50-55° C.) liquid. In the step S6, the single batch dosage of the second refining agent is between 12.5 mg and 50 mg, and its purity is between 97% and 99%. For example, the single batch dosage of the first refining agent can be 12.5 grams, 25 mg, 37.5 mg, or 50 mg. And, in a feasible embodiment, the first second refining agent can be, for example, pyrrole, 1-(2-bromoethyl)-1H-pyrrole, 2-(trichloroacetyl)pyrrole, or pyrrole-3 -Dibromothiophene, 3-bromothiophene, 3-bromothiophene-2-hydroxy acid, 2,3-dibromothiophene, 3,4-dibromothiophene , 2,5-dibromothiophene, or 2,4-dibromothiophene and other thiol derivatives.

Therefore, after the step S6 is completed, samples can be taken from the sixth mixed solution to obtain a plurality of reduced platinum particles. At this time, the platinum weight percentage of the sixth mixed solution will increase to 99-99.9 wt%. In other words, at least one platinum derivative in the original platinum-containing waste liquid has almost completely decomposed, so that the sixth mixed liquid is full of platinum particles.

After step S6 is completed, the method flow is followed by steps S7-S8: a platinum metal powder containing a plurality of platinum particles is filtered out from the sixth mixed solution by air suction filtration, and then the platinum metal powder is washed and dried . When performing the step S8, ethanol, RO pure water or deionized water can be used as the washing solution for washing the platinum metal powder. It is worth noting that the platinum particles have a micron-scale size, and their purity is between 99% and 99.9%. In other words, the method for recovering platinum disclosed in the present invention is not suitable for recovering platinum metal powder with nanoscale size from platinum-containing waste. It should be added that after the suction filtration is completed, the first refining agent and the second refining agent in the filter bottle can be recovered and reused.

Thus, the above has completely and clearly described a method for recovering platinum of the present invention. However, it must be emphasized that what is disclosed in the aforementioned case is a preferred embodiment, and all partial changes or modifications derived from the technical ideas of this case and easily deduced by those skilled in the art will not deviate from this case. scope of patent rights.

S1~S8: steps

Fig. 1 is a flow chart of a method for recovering platinum of the present invention.

S1~S8: steps

Claims (15)

A method for reclaiming platinum, comprising the following steps: (1) adding a leaching solution into a container containing a platinum-containing waste liquid to form a first mixed liquid; wherein, the platinum-containing waste liquid contains platinum (Pt) and/or an acidic liquid containing at least one platinum derivative and free of gold and/or silver, and having a platinum weight percentage ranging from 0.1 wt% to 20 wt%; (2) adding a first solvent to the vessel to obtain A second mixed solution, then uniformly stirring the second mixed solution at room temperature; (3) adding a second solvent to the container to obtain a third mixed solution, then uniformly stirring the third mixed solution at room temperature (4) adding an alkaline reducing agent to the container to obtain a fourth mixed solution, and then uniformly stirring the fourth mixed solution at a first treatment temperature ranging from 40° C. to 45° C.; (5 ) adding a first refining agent to the container to obtain a fifth mixed solution, and then uniformly stirring the fifth mixed solution at the first treatment temperature; (6) adding a second refining agent to the container to obtain a The sixth mixed solution, then uniformly stirring the sixth mixed solution at a second treatment temperature ranging from 50°C to 55°C; (7) using a suction filtration method to filter a platinum metal containing a plurality of platinum particles The powder is filtered out from the sixth mixed solution; and (8) washing and drying the platinum metal powder; wherein, the first solvent is selected from ethanol: ethylene glycol, ethanol: isopropanol, ethanol: n-butanol , ethanol: pentanol, and ethanol: any one of the group consisting of tetrahydrofuran; Wherein, the second solvent is selected from the group consisting of formic acid: methyl formate, formic acid: propyl formate, acetic acid: ethyl acetate, acetic acid: butyl acetate, and propionic acid: methyl propionate Any one; Wherein, the basic reducing agent is selected from sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium citrate, potassium citrate, sodium formate, potassium formate, sodium acetate, potassium acetate, propane Any one of the group consisting of sodium propionate and potassium propionate; wherein, the 3-(bromomethyl)thiophene, 3-(bromoacetyl)thiophene, 2-(2-bromoacetyl) The group consisting of thiophene, 2-bromo-3-(bromomethyl)thiophene, 2,3-dibromophenyl[b]thiophene, and 2,5-dibromodithiophene[3,2-b]thiophene Any first refining agent in the group is selected from; wherein, the second refining agent is selected from pyrrole, 1-(2-bromoethyl)-1H-pyrrole, 2-(trichloro Acetyl) pyrrole, pyrrole-3-hydroxy acid, 2-bromothiophene, 3-bromothiophene, 3-bromothiophene-2-hydroxy acid, 2,3-dibromothiophene, 3,4-dibromothiophene, 2 , any one of the group consisting of 5-dibromothiophene and 2,4-dibromothiophene. The method for recovering platinum as claimed in item 1, wherein, in the platinum-containing waste liquid, platinum is the first metal, and the platinum-containing waste liquid further contains at least one second metal, and the at least one second metal is present in the The concentration in the platinum-containing waste liquid is not more than 12wt%. The method for recovering platinum as described in Claim 1, wherein the platinum derivatives include platinum oxide (PtO), platinum dioxide (PtO ₂ ), platinum oxide (Pt ₃ O ₄ ), dichloride Platinum (PtCl ₂ ), platinum tetrachloride (PtCl ₄ ), platinum hexachloride (PtCl ₆ ), chloroplatinic acid (H ₂ PtCl ₆ ), platinum acetate (Pt(CH ₃ COO) ₂ ), and platinum sulfide ( At least one platinum compound in the group consisting of PtS). The method for recovering platinum as claimed in claim 1, wherein the platinum particles have a micron size, and the purity thereof is between 99% and 99.9%. The method for recovering platinum as described in claim 1, wherein the container is made of a material, and the material is selected from pyrex glass (Pyrex glass), Duran glass (Duran glass), polystyrene Any one of the group consisting of vinyl, and polyethylene terephthalate. The method for recovering platinum as described in Claim 1, wherein the leaching solution is aqua regia or aqua regia Lefort. The method for recovering platinum as described in Claim 1, wherein, in the step (1), the single batch consumption of the platinum-containing waste liquid is between 1.5 liters and 3.5 liters. The method for recovering platinum as described in Claim 1, wherein, in the step (2), the single batch consumption of the first solvent is between 0.5 liter and 1 liter. The method for recovering platinum as claimed in item 8, wherein the first solvent has a volume mixing ratio, and the volume mixing ratio is selected from 1:1, 2:1, 4:1, and 5:1 Any of the groups that make up the group. The method for recovering platinum as described in Claim 1, wherein, in the step (3), the single batch consumption of the second solvent is between 0.1 liter and 0.25 liter. The method for recovering platinum as claimed in item 10, wherein the second solvent has a volume mixing ratio, and the volume mixing ratio is selected from 1:1, 2:1, 4:1, and 5:1 Any of the groups that make up the group. The method for reclaiming platinum as claimed in item 1, wherein, in the step (4), the single batch dosage of the alkaline reducing agent is between 50 grams and 200 grams, so that the alkaline reducing agent There is an overnormal concentration in the fourth mixed solution. The method for recovering platinum as described in claim item 1, wherein, in the step (5), the single batch dosage of the first refining agent is between 25 mg and 100 mg, and its purity is between 95 % to 99%. The method for recovering platinum as described in claim item 1, wherein, in the step (6), the single batch dosage of the second refining agent is between 12.5 mg and 50 mg, and its purity is between 97 % to 99%. The method for reclaiming platinum as claimed in item 1, wherein, in the step (8), the platinum metal powder is washed with a washing liquid, and the washing liquid is selected from ethanol, RO pure water and Any one of the group consisting of ionized water.

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